The president nominates candidates to the Supreme Court, but the Congress must approve all nominations. Once approved, justices serve lifetime terms. Many Supreme Court justices serve for decades, although the average tenure of the 112 current and former justices is 16 years. Chief Justice John Marshall was the longest serving justice, remaining on the bench for more than 34 years. Justices have ranged between 44 and 68 years of age at the time of their appointment.

The Supreme Court’s purpose is to interpret the Constitution, and the court has been involved in deciding several cases with far-reaching implications. Among the most important rulings issued by the court were the 1966 ruling in Miranda v. Arizona, which established the need for law enforcement to advise arrested citizens of their rights, and the 1973 ruling in Roe v. Wade, which legalized abortion.